usemem: add write-signal-read mode

As suggested by Ying, a new switch is added to usemem:
-W|--write-signal-read
  Let processes do read when received a signal after write.
  usemem should be started as:
  usemem -n $nr_task -W -d -p pidfile $memsize
  -d to detach and -W to specify these detached processes need to do
  read when received the SIGUSR1 signal after the normal write. -p to
  specify where to save these detached process IDs so that they can
  be signalled later.

With the above added switch, the swap in case can be done as:
1 start N processes to do write and then detach and wait for signal to
  resume to do read;
2 start N processes to do write to push the memory occupided in 1) to
  swap space. When done, send SIGUSR1 with kill to those detached
  processes to resume them to do read(hence, causing swap in).

Note that for swap in case, the start time has to be set after the
detached processes got the resume signal SIGUSR1.

Signed-off-by: Aaron Lu <aaron.lu@intel.com>
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>

1 files changed, 38 insertions, 11 deletions

diff --git a/usemem.c b/usemem.c
index 9af6bdc..2de0dbd 100644
--- a/usemem.c
+++ b/usemem.c
@@ -54,6 +54,7 @@ unsigned long opt_bytes = 0;
 unsigned long unit = 0;
 unsigned long step = 0;
 unsigned long *prealloc;
+unsigned long *buffer;
 int sleep_secs = 0;
 time_t runtime_secs = 0;
 struct timeval start_time;
@@ -70,6 +71,7 @@ int opt_shm = 0;
 int opt_remap = 0;
 int opt_mincore = 0;
 int opt_mincore_hugepages = 0;
+int opt_write_signal_read = 0;
 int sem_id = -1;
 int nr_task;
 int nr_thread;
@@ -112,6 +114,7 @@ void usage(int ok)
 	"    -E|--remap          remap file virtual memory\n"
 	"    -N|--mincore        get information about pages in memory\n"
 	"    -H|--mincore-hgpg   get information abt hugepages in memory\n"
+	"    -W|--write-signal-read do write first, then wait for signal to resume and do read\n"
 	"    -h|--help           show this message\n"
 	,		ourname);
 
@@ -252,7 +255,7 @@ void update_pid_file(pid_t pid)
 	if (!pid_filename)
 		return;
 
-	file = fopen(pid_filename, "w");
+	file = fopen(pid_filename, "a");
 	if (!file) {
 		perror(pid_filename);
 		exit(1);
@@ -352,7 +355,7 @@ int runtime_exceeded(void)
 {
 	struct timeval now;
 
-	if (!runtime_secs)
+	if (!runtime_secs || start_time.tv_sec == 0)
 		return 0;
 
 	gettimeofday(&now, NULL);
@@ -469,6 +472,9 @@ unsigned long do_unit(unsigned long bytes, struct drand48_data *rand_data)
 		rw_bytes = bytes / 8;
 	}
 
+	if (opt_write_signal_read)
+		buffer = p;
+
 	for (rep = 0; rep < reps; rep++) {
 		if (rep > 0 && !quiet) {
 			printf(".");
@@ -557,6 +563,8 @@ static void output_statistics(unsigned long unit_bytes)
 	write(1, buf, len);
 }
 
+static void wait_for_sigusr1(int signal) {}
+
 long do_units(void)
 {
 	struct drand48_data rand_data;
@@ -584,15 +592,35 @@ long do_units(void)
 			break;
 	} while (bytes);
 
-	if (unit_bytes)
+	if (!opt_write_signal_read && unit_bytes)
 		output_statistics(unit_bytes);
 
+	if (opt_write_signal_read) {
+		struct sigaction act;
+		memset(&act, 0, sizeof(act));
+		act.sa_handler = wait_for_sigusr1;
+		if (sigaction(SIGUSR1, &act, NULL) == -1) {
+			perror("sigaction");
+			exit(-1);
+		}
+	}
+
 	if (opt_detach && up(sem_id))
 		perror("up");
 
 	if (sleep_secs)
 		sleep(sleep_secs);
 
+	if (opt_write_signal_read) {
+		sigset_t set;
+		sigfillset(&set);
+		sigdelset(&set, SIGUSR1);
+		sigsuspend(&set);
+		gettimeofday(&start_time, NULL);
+		unit_bytes = do_rw_once(buffer, opt_bytes, &rand_data, 1, NULL, 0);
+		output_statistics(unit_bytes);
+	}
+
 	return 0;
 }
 
@@ -668,7 +696,7 @@ int main(int argc, char *argv[])
 	pagesize = getpagesize();
 
 	while ((c = getopt_long(argc, argv,
-				"aAf:FPp:gqowRMm:n:t:ds:T:Sr:u:j:EHDNLh", opts, NULL)) != -1)
+				"aAf:FPp:gqowRMm:n:t:ds:T:Sr:u:j:EHDNLWh", opts, NULL)) != -1)
 		{
 		switch (c) {
 		case 'a':
@@ -762,6 +790,10 @@ int main(int argc, char *argv[])
 			opt_mincore_hugepages = 1;
 			break;
 
+		case 'W':
+			opt_write_signal_read = 1;
+			break;
+
 		default:
 			usage(1);
 		}
@@ -773,13 +805,8 @@ int main(int argc, char *argv[])
 	if (optind != argc - 1)
 		usage(0);
 
-	if (pid_filename && nr_task) {
-		fprintf(stderr, "%s: pid file is only for single process\n",
-			ourname);
-		exit(1);
-	}
-
-	gettimeofday(&start_time, NULL);
+	if (!opt_write_signal_read)
+		gettimeofday(&start_time, NULL);
 
 	opt_bytes = memparse(argv[optind], NULL);